One big factor might be the time of year that you are there. If it's the heat of summer, then taking a break at lunch or early evening to get out of the sun for a while can seem like a great idea, regardless of what your usual schedule is at home....allowing you to shift some added park time to the evening, when things cool down at least a bit.
Our biggest factor tends to be our ten-year old's stomach. Mom, dad and 13-year old are all pretty flexible when it comes to eating times. But if the youngster gets hungry, she goes from Jekyl to Hyde (or whichever is good to bad!) and needs to be fed...which sometimes means eating just enough to hold her over, but then that turns out to be just enough that she's not hungry when "real" dinner is served, so she orders or eats very little and then is hungry again at 10:00 that night, wondering when we were going to feed her dinner. Ha!